Intense Questions about Tax Liens

I am a beginner investor with lots of questions. Please forgive me! I have several questions pertaining to tax liens. First, I do understand that you can pay people's taxes and wait for the redemption period to foreclose to get the property.
I read somewhere that tax liens have priority over any other mortgage lien even first mortgage? Is this TRUE? If so, this leads into my next series of questions, if I buy a tax lien on a property were the 1st mortgage is current, what besides the interest of the tax lien would be beneficial to me I would have to wait the redemption period before I could even foreclose on the property. If I was the mortgage company and the tax lien holder notified me and stated that they have a tax lien on the poperty I would say so? I would not care because their mortgage is currently being paid and you cant foreclosed until the redemption period so why would this intimidate the 1st mortgage people so immediatley?

Question 2: Same scenario as in question 1 but the 1st mortgage is deliquent (about to go into foreclosure), then the tax lien holder would have to call the 1st mortgage people and discount the mortgage so he can have control of the property and foreclose immediately instead of waiting for the redemption period of the tax lien to expire, right? The reason why I ask this is say a person is behind on his mortgage and the mortgage company wants to foreclose (1st mortgage) he is not going to say "Wait a minute, there is a tax lien on the property, we can't foreclose" It doesn't really seem like the tax lien is really in first position. The 1st mortgage company will foreclose and all other liens are wiped out even the tax lien holder lien, right ? In this scenario the tax lien holder is going to get nothing right? The tax lien holder must be aware of the mortagages and discount it so he can foreclose get the property without having to wait the redemption period, right?

Question 3: Same scenario as question 1 but the 1st mortgage is current and there is a junior lien on the property, now in order for the owner of the junior lien to foreclose on the property he must move into first position he must pay the owner of the tax lien off first right? No, because would he then have to wait the redemption period to foreclose or should he should contact the 1st mortgage and pay it off so he can move into first position so he can foreclose. This goes into my question, can a junior lien holder pay off the first lien to 1st mortgage so he can move into first and foreclose, then the redemption period of the tax lien is invalid right?

Really, can a junior lien move into the 1st mortgage position so he can foreclosure a waive the redemption period of the tax lien? or can the junior lien just foreclose on the property and wipe out all other liens on the property including tax lien and 1st mortgage.

I am so sorry for bending yah's ear, but I am just confused. Thanks in advance!